the vice president of technology for the fremont company says his company makes the tenergy wasry. it's used by hobbyists to power remote controlled car and can be bought at hobby shops and online. >> horrified and appalled, appalled and shocked. these batteries are largely used for toys. cars and trucks and to see it used in such a way, just horrifying. >> he says his company has sold tens of thousands of the batteries. he says tracing who bought the one that might have been used in the bombings would be near impossible. however, he said tenergy has contacted boston police and the fbi to offer their assistance. our coverage continues on our website, nbc bay area.com. it's updated around the clock. >>> just into our newsroom, federal agents say kenneth curtis of mississippi has been arrested as the suspect connected to poison letters recently mailed to president obama and a u.s. senator. both those letters tested positive for ricin. ricin is a deadly poison made from castor beans. it can kill within 36 hours and there's no known antidote. an fbi spokesperson says at this point they